One the amazing miracles in Quran, is how God is subtle yet clear in proving the Welayah of Ali (a). I already alluded to Ulil-Amr verses, but let's go two different themes. One is the reward theme and the other which this post will be about is the prayer of Musa (a) regarding Harun (a) and how the pertains to Ali (a) and Mohammmad (s).
(Suratal A'araaf)
By the Name of God, the Compassionate, the Merciful, Alif Lam Mim Saud, a book we have brought down to you
so there be no straightness in your breast that you may warn by it and a reminder to the believers.
(Suratal Hijr)
And indeed we know
your breast is straightened by what they say.
(Suratal Isra)
And say God cause me to enter an honest entering and go forth an honest going forth, and give me from you a
helping authority.
(Suratal Inshira)
By the Name of God, the Compassionate, the Merciful,
did we not expand you your breast?
Now a person may think, this has nothing to do with Ali and it would be a stretch to say so. But why emphasize on paraphrasing Moses words to match this:
[Shakir 20:25] He said: O my Lord! Expand my breast for me,
وَيَسِّرْ لِي أَمْرِي {26}
[Shakir 20:26] And make my affair easy to me,
وَاحْلُلْ عُقْدَةً مِنْ لِسَانِي {27}
[Shakir 20:27] And loose the knot from my tongue,
يَفْقَهُوا قَوْلِي {28}
[Shakir 20:28] (That) they may understand my word;
وَاجْعَلْ لِي وَزِيرًا مِنْ أَهْلِي {29}
[Shakir 20:29] And give to me an aider from my family:
هَارُونَ أَخِي {30}
[Shakir 20:30] Haroun, my brother,
اشْدُدْ بِهِ أَزْرِي {31}
[Shakir 20:31] Strengthen my back by him,
وَأَشْرِكْهُ فِي أَمْرِي {32}
[Shakir 20:32] And associate him (with me) in my affair,
كَيْ نُسَبِّحَكَ كَثِيرًا {33}
[Shakir 20:33] So that we should glorify Thee much,
وَنَذْكُرَكَ كَثِيرًا {34}
[Shakir 20:34] And remember Thee oft.
وَيَضِيقُ صَدْرِي وَلَا يَنْطَلِقُ لِسَانِي فَأَرْسِلْ إِلَىٰ هَارُونَ {13}
[26:13] And my
breast straitens, and my tongue does not reach, therefore send Thou to Haroun (to help me);
وَأَخِي هَارُونُ هُوَ أَفْصَحُ مِنِّي لِسَانًا فَأَرْسِلْهُ مَعِيَ رِدْءًا يُصَدِّقُنِي ۖ إِنِّي أَخَافُ أَنْ يُكَذِّبُونِ {34}
[Shakir 28:34] And my brother, Haroun, he is more reaching in tongue than I, therefore send him with me as an aider, verifying me: surely I fear that they would reject me.
If we gather these verses, the ones with Mohammad and ones with Moses, the ones with Mohammad are making clear that Aaron was not better in conveying due to a fault of Moses, but that it was "due to what they say", that Moses had such constriction on his heart.
And the verses with Moses shows Mohammad also never had a psychological weakness or anything, but that, his heart was straightened and constrained by what people were saying.
It was due to the circumstances they were both in that such constraint took place.
The relief of this burden weighing heavily on their backs, strengthening them and their affair, was through the conception of
succession in Islam.
Why didn't Moses say yes I can do it, but right away realized he needed a helper to convey better? Again, not due to lack of confidence or ability to convey or speak, but the circumstances.
So this is one of the themes in Quran and shows wisdom with respect to succession.
And while Aaron name appears 20 times in Quran (Suratal Taha is 20th Surah as well), his name beside Moses appears exactly twelve times.
To emphasize more on this:
By
the name of Allah, the Beneficent, the Merciful.
Have We not expanded for you your breast, 1
And taken off from you your burden, 2
Which pressed heavily upon your back, 3
And exalted for you your esteem? 4
Surely with difficulty is ease. 5
With difficulty is surely ease. 6
So when you are free, set. 7
And make your Lord your exclusive object. 8
The 6th verse is an allusion to the name Seth and in the same way he was set by God and Adam (a), Mohammad (s) is to set his successor. Keeping in mind the prayer of Musa (a) with Haroun (a), "the name of God" is also an allusion to that Ali (a) is that like Samuel (a) means name of God.
Seth (a) and Samuel (a) names don't appear in the Quran in Hebrew form but can be said to be alluded here in this chapter.
Next I will expand on the reward verses.